(Sergeant's) The Sentry Calming Diffuser releases Good Behavior pheromones into your home to provide cats with calming sensations. Pheromone technology has been proven to modify stress-related bad behavior such as inappropriate marking, excessive meowing, and scratching. Sentry Calming Diffuser plugs into wall outlet and lasts up to 30 days. Refills for diffuser may be purchased separately. Lavender chamomile fragrance.